Millions of needles are used every day in hospitals, clinics and medical offices for taking blood samples, injecting fluids via a catheter, and for other purposes in the practice of clinical medicine. The needle is part of an overall assembly packaged in a suitable sterile container. The container is broken into, the needle assembly is removed, and the needle is withdrawn from its protective cover or cap. The needle is then used on a patient, as for example, in conjunction with a syringe.
Thereafter, the nurse (or other health care provider) often picks up the cap in one hand--and the used needle in the other hand--and inserts the used needle into the cap. Sometimes, and especially if the nurse is distracted or in a hurry, the nurse will miss the cap completely and accidentally stick her (or his) hand with the used needle. Some nurses even hold the cap between their lips, then insert the used needle into the cap; unfortunately, they sometimes miss and stick their lips or tongue!
Accordingly, there is a definite risk of acquiring the deadly human immunodeficiency virus (HIV) or "AIDS" virus from a patient. As reported by R. Marcus, "Surveillance Of Health Care Workers Exposed To Blood From Patients Infected With the Human Immunodeficiency Virus", New England Journal of Medicine, 1988, the risk of HIV transmission from a single needle-stick injury is approximately 0.4%. The risk of transmission of the hepatitis-B virus is even higher.
The results reported by Marcus are similar to a study conducted by the Needle Stick Surveillance Committee of the Centers For Disease Control ("CDC"). Their study showed that out of around 3,900 cases of needle sticks incurred by health care providers (where AIDS patients were involved) 13 health care providers--roughly 1 out of 300--subsequently tested HIV positive.
Even if routine testing of patients is performed, some HIV-infected individuals would test "false negative" since there is a six-month incubation period for the HIV virus. Because of the difficulty in determining which patients are infected with HIV, the CDC has issued guidelines called "Universal Precautions". Under these Universal Precautions, all patients are treated as if infected with the AIDS virus; and all bodily fluids which may be contaminated with blood, semen or other internal body fluids are assumed to be infectious.
The greatest risk of transmission occurs from parenteral exposure (i.e., through broken skin) to contaminated instruments. Eighty percent (80%) of exposures reported by Marcus were due to needle-sticks and eight percent (8%) were due to cuts with HIV contaminated instruments. Thirty-five percent (35%) of needle stick injuries involve disposable syringes, and twenty-five percent (25%) involve intravenous tubing and needle assemblies (as reported by Jagger et al "Rates Of Needle-Stick Injury Caused By Various Devices In A University Hospital, New England Journal of Medicine, 1988). Furthermore, seventeen to thirty percent (17-30%) of these needle stick injuries occur while recapping used needles (from Marcus, Jagger).
As a result, the CDC has recommended that recapping of needles be abandoned, and that needles be promptly discarded into a puncture-resistant "sharps" container. Despite widespread promulgation of these recommendations by the CDC, health care workers continue to recap 21.5% of used needles (as reported by Kaczmarek et al, "Multistate Investigation Of Needle-Handling by Health Care Workers", MMJ, 1991).
If a health care worker is exposed to the blood of a known AIDS patient, periodic testing is required (more or less indefinitely) to determine if the worker has become HIV positive. This is an inconvenient, worrisome, costly and time-consuming procedure. Besides, the very threat of becoming HIV positive from a needle stick injury is disconcerting and distracting and interferes with the worker's concentration on the job. Additionally, the health care worker may refrain from intimate relations and may delay childbearing to protect his or her partner and children from possibly acquiring the deadly AIDS virus.
Moreover, the failure to properly dispose of "sharps" has led to countless injuries among housekeeping, laundry and janitorial personnel.
The problem of safely recapping a used needle has long been recognized in the prior art. For example, U.S. Pat. No. 5,041,099 issued to Gelabert on Aug. 20, 1991, discloses a non-reusable syringe in which the cap has three splayed feet on the end thereof, and the cap is intended to remain in an upright position while recapping the needle. However, if the cap is placed on an uneven surface or on a patient's roll-away table (which is on casters) the cap will be unsteady, and the cap will fall over if the table is jarred.
Additionally, some disposable instrument trays provide a channel for placement of the needle cap. Nevertheless, the acceptance of these prior art devices has been quite limited.
Needle stick injuries remain an occupational hazard, and the risk continues to escalate as the AIDS disease multiplies. As a result, doctors, nurses and other health care workers have modified their practices or, in some cases, have quit their jobs altogether.